Internal combustion engine of the liquid fuel injection compression ignition type



Feb. 20, 1940. H. R. RICARDO 2,191,042

INTERNAL COMBUSTION ENGINE OF THE LIQUID FUEL INJECTION COMPRESSION IGNITION TYPE 7 Filed July 25, 1958 II Ill/I, {/IIIIIIIIIIIIIIIIIIIIIIIII 1? 17 Edi Abba/'40,

MYMW Patented Feb. 20, 1940 UNITED, STATES INTERNAL COMBUSTION ENGINE OF THE LIQUID FUEL INJECTION COMPRESSION IGNITION TYPE Harry Ralph Ricardo, London, England Application July 25, 1938, Serial No. 221,208 In Great Britain July 29, 1937 3 Claims.

This invention relates to improvements in or modifications of internal combustion'engines as described and claimed in the present invntors U. S. Patent No. 2,113,711. In an engine as there described and claimed, not more than 50% of the total volume of the combustion space is constituted by the chamber or pocket which lies outside the cylinder, together with the passage- -way through the plug member disposed in the mouth of this chamber, the remainder of the combustion space being constituted by the space between the face of the piston and the end of the cylinder, which space is increased locally adjacent to the orifice of the passageway through the plug.

According to the present invention the abovementioned recess is formed so that it is substantially circular in plan and it is combined with a groove which runs into this recess and enters it tangentially as viewed in plan, the outer end of the groove being located where it will be opposite the orifice of the passageway through the plug member. Thus the gases after'ignition of the charge in the external combustion chamber will pass through the passageway in the plug member into the groove and along this groove into the circular recess. By reason of the tangential entry of the roove into the recess, the gases as they pass through the groove into the recess will tend to be given a rotational swirl in the recess and the reference to the tangential" entry of the groove into the recess is to be interpr'eted as including not only constructions in various ways, but one construction according to the invention and a modification thereof are illustrated by way of example in the accompanying drawing, in which Figure 1 is a section through the upper part of a cylinder, cylinder head and piston incorporating the present invention, the section being taken in a plane containing the cylinder axis,

Figure 2 is a plan of the cylinder barrel and piston shown in Figure 1 with the head removed, the position of the combustion chamber being indicated in chain line,

Figure 3 is a section on the line 3-3 of Figure 2, and c Figures 4, 5 and 6 are views similar to Figure 2, showing several modifications according to the invention.

In the construction, illustrated in Figures 1,

2 and 3, the engine comprises a cylinder block :v

A containing a water-cooled cylinder liner A within which reciprocates a piston B, the upper end of the cylinder being closed by a cylinder head C which is also water-cooled and contains inlet and outlet ports controlled by valves, one of which is indicated at D.

Formed in the cylinder head so as to lie partly to one side of but to overlap the cylinder bore, is a sprocket C the upper end of which is, as shown, approximately hemispherical, while its lower end, which lies adjacent to the cylinder bore, is of generally cylindrical form and contains a plug E having a flange E engaged by a screwthreaded ring E which serves to retain the plug in place. The external contour of the plug conforms generally to the internal contour of the lower part of the pocket, the plug being formed, however, so that there is a small air space between its circumferential surface and the surface of the cooled wall surrounding it, so that the transference of heat from the plug to the cooled surrounding wall is limited.

Formed in the plug is an approximately hemispherical recess E which, with the hemispherical end of the pocket, forms an approximately spherical combustion chamber C into which leads tangentially a passage E formed in the plug so that its lower end communicates with the cylinder bore. I

Formed in the face of the piston B is a recess B which, viewed in plan, is of circular form, the bottom of this recess 13 being approximately flat and being curved up at its edges to run smoothly into the side 13 thereof. Also formed in the face of the piston is a groove B one end of 1 which runs tangentially into the recess as shown, while its other end lies immediately beneath the lower end of the passage E the floor of this groove being curved at its outer end, as shown at B so as to lead the hot gases flowing through the passage E smoothly along the groove'B into the recess B As will be seen, the longitudinal axis 'or the groove B if extended, passes approximately through the axis of the piston and the arrangement is such that the hot gases flowing from the combustion chamber C through the passage E will pass through the groove B into the re-' cess B in such a manner as to rotate about the axis of this recess.

, In the alternative construction indicated in Figure 4a recess B similar in formto the recess B is formed in the face of the piston B so as to be approximately coaxial therewith and a groove B of the same general form as, but somewhat longer than, the groove B leads tangentially into the recess 13 the outer end of the groove B lying beneath the lower end of the constructed and arranged similarly to the combustion chamber but with the axis of the a plane which is tangential to a circle having the runs smoothly intothe circumference B of the recess B may constitute a continuation of the axis of the cylinder for centre.

In this construction also the hot gases flowing from the passage E will pass along the groove B so as to enter the recess B tangentially and thus be caused to rotate about the axis of this recess.

The dimensions of the recess and groove may vary to suit requirements. As an example of one constructional arrangement in which the diameter of the piston is 4.75 inches, howeverythe diameter of the recess, viewed in plan, may be 2.25 inches at its margin, which lies in the plane of the piston face. The flat-bottomed floor B of the recess may then be approximately 1.75 inches in diameter and the recess at this floor may have a depth of 0.40 inch. In a construction such as that shown in Figures 1, 2 and 3 with the parts having the above dimensions, the length of the groove, measured from the axis of the piston to the outer end of the groove where it lies adjacent to the periphery of-the piston, may be approximately 2.25 inches, the groove having a width of, say, 0.75 of an inch.. In this construction also the distance of the axis of the recess B from that diameter of the piston which coincides with the longitudinal axis of the groove B may be, say, 0.75 of an inch, while the distance of this axis from the diameter of the piston which lies at right angles to the .diameter referred to above may be, say, 0.375 of an inch.

It is to be understood that the above is given purely by way of example and that the dimensions of the recess and of the groove may be varied to suit requirements. Thus, for example, in some cases, while both sides of the groove viewed in plan are straight'up to the point where the shorter side meets the circumference of the .recess, the other side'may be arranged so that if continued straight it would not meet the circumference of the recess, thisother side being curved inwards from the pointin the length of the groove where the first side meets the oilcumference of the recess towards the axis of the recess so as to run smoothly into the circumferenceof the recess. Thus, in such an arrangement, as shown for example in Figure 5, which; is otherwise similar to Figure 4, the circumference of the recess B and the side of the groove tion 3*, which constitutes one" side of the groove,

is straight. Alternatively, as shown for example in Figure 6, the. side B of the groove 13', which spiral referred to, the opposite side B of the groove being similarly formed, when the groove as a whole may be regarded as of spiral form running smoothly into the recess much in the same way as the outletof a centrifugal pump enters the blade chamber. In a further modification otherwise similar to Figure'fi, the side B of the groove may be straight.

It is to be understood that where the external combustion chamber and plug are situated at the side of the cylinder and not in the cylinder head, according to an alternative arrangement indicated in the specification of the above-mentioned U. S. Patent 2,113,711 the improved recess and groove according to the invention may then be formed in the head of the cylinder, so that the gases issuing from the passageway through the plug will enter the groove and pass thence into the circular recess wherein these gases will tend to have imparted to them a rotational swirl about the axis of the recess.

What I claim is:

l 1. An internal combustion engine of the liquid fuel injection compression ignition type comprising in combination a cylinder, adetachable head for the cylinder, a piston in the cylinder, the opposed faces of the head and piston adapted to be disposed closely together at the end of the compression stroke of the piston, thereby reducing the clearance between them as far as is permitted by mechanical clearance, a pocket-like combustion chamber formed and disposed externally of the cylinder and opening toward the same, a plug member arranged in the mouth of said chamber and having a passageway therethrough, said passageway terminating in an orifice, a fuel jet device disposed in said chamber for delivering a charged fuel towards a point in the wall of said chamber, a recess formed in one of the said opposed faces, said recess, which is open to the cylinder bore, being so formed that it is substantially circular in plan and being combined with a groove which runs into said recess and enters it tangentially, the outer end of said groove being adapted to lie opposite to said orifice at least at the end of the compression stroke, said recess with said groove constituting a local increase in the otherwise reduced clearance between the piston and cylinder head, the total combustion space available at the end of the a compression stroke being comprised by the volumetric content of the external chamber, the

passageway through the plug, the recess and the remainder of the clearance between the face of the piston and the end of the cylinder, of which total combustion space not more than is in the external chamber and the said passageway.

2.'An internalcombustion engine as claimed in claim 1, in which the side wallof the groovewhich meets the circumference of :the recess at an' acute angle is approximately straight, while the other side wall, which runs smoothly into the circumference of the recess, is for a part of its qrlength measured from the outer end of the groove substantially straightand tangential to a circle having the centre of the recess for axis, but of larger diameter than the recess, and thereafter Ayis curved inwards towards the axis of the recess after the. manner of a volute so as to merge and that side wall of the groove which runs smoothly into the side wall of the recess together constitute a wall which, viewed'in plan, is of spiral or volute form.

' HARRY RALPH RICARDO. 

